How this calculator works
Each plant needs a share of the bed: its spacing squared in a grid. In a staggered layout, each row is offset by half a space, so the plants sit at the corners of equilateral triangles, and each plant takes only 0.866 of the area. The count is the bed area divided by that share.
Worked example: a 10 × 10 ft bed (100 ft²) at 12 in spacing takes 100 plants in a grid, or 116 staggered. With 5% spares, buy 105 or 122.
Plants needed per 100 square feet
| Spacing | Square grid | Staggered |
|---|---|---|
| 6 in | 400 | 462 |
| 8 in | 225 | 260 |
| 12 in | 100 | 116 |
| 15 in | 64 | 74 |
| 18 in | 45 | 52 |
| 24 in | 25 | 29 |
| 36 in | 12 | 13 |
Tips before you buy
- Check the plant tag for the mature width. A shrub that grows 4 ft wide needs far more than 12 in between plants.
- Edge plants half a spacing from the border so the outer plants are not crowded out.
- Bulbs are planted much closer than other plants: usually two to three bulb widths apart, in clumps for a natural look.
- Mulch around young plants to hold in moisture and suppress weeds while they fill in.
Tools & materials for this project
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Frequently asked questions
How many plants per square foot?
Divide 144 by the spacing squared (in inches). At 12 in spacing you get 1 plant per square foot, and at 6 inches it is 4 plants per square foot.
Is a staggered layout better than a grid?
Staggered layouts fit about 15% more plants in the same area and fill in evenly, which suits groundcovers. A grid is easier to lay out, and suits rows in a vegetable garden.
How far apart should I plant perennials?
Check the tag: it depends on the mature spread, and ranges from 6 inches for small groundcover to 3 feet or more for large perennials and shrubs.
Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.